Bài 4: a)x²y²+2x²+y²+2 b)a²-b²+a-b

2 câu trả lời

a) x²y² + 2x² + y² + 2

= (x²y² + y²) + (2x² + 2)

= y².(x² + 1) + 2.(x²+1)

= (x² + 1).(y²+2)

b) a² - b² + a - b

= (a - b).(a + b) + (a - b)

= (a - b).(a + b + 1)

`x^2y^2+2x^2+y^2+2`

`=x^2(y^2+2)+(y^2+2)`

`=(y^2+2)(x^2+1)` 

`a^2-b^2+a-b`

`=(a-b)(a+b)+(a-b)`

`=(a-b)(a+b+1)`